IMGD 3100 Novel Interfaces for Interactive Environments: Physical Input

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1 IMGD 3100 Novel Interfaces for Interactive Environments: Physical Input Robert W. Lindeman Associate Professor Human Interaction in Virtual Environments (HIVE) Lab Department of Computer Science Worcester Polytechnic Institute

2 Overview Manipulating Physical controls is different from manipulating virtual controls Handling them is different Brain activity is different Uses may be different We need to design to best suit the application, user, and environment Tap into previous experience Support adequate expressiveness Automate what we can Provide multi-modal redundancy 2

3 Physical vs. Virtual Controls In the past, physical controls were more common Now, virtual controls are as common Examples? Many virtual tools mimicked physical tools However, since physical manipulation requires touching, virtual versions are often flawed 3

4 In-Class Exercise (or Google: Interface Hall of Shame ) Click on Selecting the wrong control 4

5 The Brain/Hand Connection Every interface has to be learned Could be a short learning time though Over time, some people master an interface to the point where they don t really think about it anymore (muscle memory) Guitar/piano players Remembering phone numbers Goal of Interaction Design To allow users to perform actions instinctively and without the need to consider each action but to instead consider its larger consequence. Make it so your users can develop (good) habits 5

6 A Button is Much More than Just a Button An electrical object Pushing it closes the circuit, alerting the Arduino An interactive object More common than knobs today, because many things we control are digital Thermostat, mp3 players, phones Buttons are quick too A state in program code We address the button using the state of a pin 6

7 A Knob is Much More than Just a Knob Buttons are digital (ON/OFF) Analog gives us more expressiveness Knob as Interactive Object Represents a range of values Less precise than a button Some knobs change the values in fixed increments Implemented as a potentiometer for us Could be "soft potentiometers" softpotsplash/softpot.html 7

8 Lights Tell us the state of something Charging state of a battery Progress of an activity State of a larger device 8

9 Touch and Vibration Piezoelectric sensors (or just piezos) Use for sensing Pressure Acceleration Strain Force Crystals generate an electric potential in response to stress More current is returned when bent 9

10 Detecting Motion Easy and fun Use when someone approaches your installation Proximity on phones Passive Infrared (PIR) sensor Senses rapid changes in the presence of IR energy Caused by people coming into the scene 9 or 10 micrometer wavelength 10

11 Reading User Distance Two main technologies Ultrasonic (range finders) How long it takes a wave to return Magnitude is proportional to distance Infrared Two parts: emitter and receiver Angle of beam returning is measured to estimate distance Used in digital cameras 11

12 Detecting Forces and Tilt Accelerometers When you push on the gas pedal, you sink back into your seat Measure the change in angle between a pendulum and gravity Two-axis, three-axis accelerometers They are noisy, so averaging is a good idea 12

13 Binary Numbers Decimal vs. Hexadecimal vs. Binary 13

14 Further Reading Chapter 7 from Programming Interactivity Interface Hall of Shame 14